98 PHYSOSTOMI. 



Variety d. — Salmo nigripinnis, Plate CXV, fig. 2. 



Salmo nigripinnis, Giinther, Catal. vi, p. 96 ; Houghton, British Freshwater 

 Fishes, p. 120, c. fig. 



I now propose alluding to Salmo nigripinnis, Giinther, which is similar to 

 S. Cormihiensis as described by Borlase, Artedi, etc., and which for many reasons 

 may be considered as a variety which in suitable localities frequently 

 developes into S. ferox. I have been most liberally supplied with specimens 

 from Cardiganshire, through the kindness of Sir Pryse Pryse ; and among them 

 is one form which was alluded to by Barrington, in the Transactions of the 

 Boyal Society for 1774, as the " Hog-backed Trout of Plinlimmon " (Plate 

 CXI, fig. 1), which Dr. Giinther, as I believe correctly, considered identical with 

 his 8. nigripinnis. My example, which is about 11 inches in length, is peculiarly 

 interesting, as forming a link between 8. nigripinnis and 8. ferox, pertaining 

 partly to one form and partly to the other. The following are the differences 

 noted in the British Museum Catalogue : — 



Salmo nigripinnis. Salmo ferox. 



D. 14, A. 12, P. 13, Ceec. 36-42 ; D. 14, A. 10-11, P. 16, Ceec. 44-49 ; 



Yert. 57-59. Vert. 58-59. 



Head small. Snout not much pro- Head of moderate size. Snout 



duced in males. No mandibular hook much produced in males. Mandibular 



observed. Head of vomer with a trans- hook when spawning. Head of vomer 



verse band of teeth, on body generally small, toothless ; body with a double or 



in a single series. Female mature at zigzag line of teeth. Caudal truncated 



7 inches. Largest example observed, at 18 inches; in larger examples 



16 inches. rounded. Female mature at 14 inches. 



Largest example observed, 31 inches. 



These reputed two species have been found residing in nearly or quite the 

 same localities in England, Scotland, Wales, and Ireland. The size of the speci- 

 mens examined is important, as tending to modify the conformation of the 

 opercular pieces, as well as of the fins, the character of the scaling, the propor- 

 tionate diameter of the eye, and the existence or the reverse of the teeth on the 

 front of the body of the vomer. The teeth being present on the anterior part 

 of the body of the vomer in the smaller 8. nigripinnis, but absent from the 

 same place in the larger ones, 8. ferox, is symptomatic of endentulation due to 

 age. The same argument applies to the mandibular hook, it being well known 

 that among the Salmonidee this production is absent in young males, as may be 

 readily observed in the parr which possess milt ready for shedding. The number 

 of pectoral rays is immaterial, as I find, even in the British Museum specimens, 

 examples of 8. nigripinnis, 8. ferox, and 8. fario possessing from 13 to 15. 



The foregoing leaves the following as Dr. Giinther's primary reasons for 

 dividing these two so-called species : — 8. nigripinnis has D. 14, A. 12 ; head of 

 the vomer-toothed, and generally a single row along the body of that bone ; caudal 

 fin with pointed lobes. 8. ferox : D. 13, A. 10-11 ;* no teeth on the head of the 

 vomer, but a double row along the body of the bone ; caudal fin truncated. 



The example of the " hog-backed trout " in my collection has D. 14, teeth on 

 the front portion of the body of the vomer, and a distinct lower limb to the 

 preopercle, thus belonging to 8. nigripinnis. Likewise A. 11, a double line of 

 teeth along the body of the vomer, and the caudal fin almost square at its extremity 

 or becoming similar to what is given as diagnostic of 8. ferox. 



I have likewise six smaller examples of 8. nigripinnis in which teeth are 

 present on the front portion of the body of the vomer and in a zigzag line along 

 the body of that bone ; the caudal fin in the smallest has pointed lobes, which 

 have become rounded in larger specimens ; the ccecal appendages varied from 

 35 to 44. In some of these fish the posterior margin of the preopercle was 



* Thompson (iv, p. 157) found D. 13-14, A. 11-12. 



